Signs are commonly used along roadways to display information to motor vehicle drivers and pedestrians. The term “sign” as used herein refers to a stand-alone article that conveys information, usually by means of alphanumeric characters, symbols, graphics, or other indicia, and that in use is mounted to an object such as a post, bracket, wall, or similar body. Specific examples include signs used for traffic control purposes (STOP, YIELD, speed limit, informational, overhead highway sign, roadside markers, etc.), street signs, guide signs, and vehicle license plates. Guide signs are those signs used to direct road users along streets and highways, to inform them of intersecting routes, to direct them to cities, towns, villages, or other important destinations, to identify nearby rivers and streams, parks, forests, and historical sites, and generally to give such information as will help them along their way in the most simple, direct manner possible.
Many signs include optically active (e.g., reflective or retroreflective) sheeting that has characters or images printed or placed thereon. The characters or images provide information that is of interest to the motor vehicle drivers or pedestrians, and the retroreflective sheeting allows the information to be vividly displayed at night. The term “retroreflective” as used herein refers to the attribute of reflecting an obliquely incident light ray in a direction antiparallel to its incident direction, or nearly so, such that it returns to the light source or the immediate vicinity thereof. Retroreflective sheeting has the ability to return a substantial portion of incident light in the direction from which the light originated. Light from motor vehicle headlamps is retroreflected by the signs, allowing the information to be read more easily by passing motorists and pedestrians. The following will be discussed with respect to retroreflective signage, but the application is meant to include non-retroreflective embodiments as well.
Typically, a conventional guide sign that includes retroreflective sheeting is manufactured as is shown in FIG. 1. First, the sign user (typically a government agency) creates a sign design and sends the sign design to a sign manufacturer. The sign manufacturer orders the required sign blank from a sign blank manufacturer and the required optically active sheeting from a sheeting manufacturer. A sign blank is a rigid substrate suitable for mounting in the intended end use application. Exemplary sign blanks include a rigid mass of metal, wood, plastic, or the like. A sign blank manufacturer will receive the sign manufacturer's order and will cut the sign blank to the required dimensions and ship the sign blank to the sign manufacturer. In the meantime, the sheeting manufacturer will produce the required optically active sheeting in the required colors, will cut the sheeting to the required widths, and will ship the optically active sheeting to the sign manufacturer.
Upon receipt of the sign blanks and the optically active sheeting, the sign manufacturer implements the following process, which is described with respect to one exemplary specific implementation. In this exemplary implementation, the desired guide sign includes four 18 inch×12 inch aluminum extrusions each having a major surface and two opposed lateral surfaces generally perpendicular to the major surface. The sign manufacturer applies retroreflective sheeting having a first color (e.g., green) to the major surface (the “front surface”) of each of four aluminum extrusions such that the green retroreflective sheeting completely covers the front surface and is wrapped around at least a portion of the two lateral surfaces. The green retroreflective sheeting is prepared by removing the release liner on the sheeting so as to expose a pressure sensitive adhesive layer. Then the green retroreflective sheeting is applied to the generally smooth, flat front surface of the aluminum extrusion so that the pressure sensitive adhesive layer contacts the front surface of the aluminum extrusion. This process is repeated for four aluminum extrusions, after which the covered extrusions are bolted together to form a multi-panel sign.
Indicia (e.g., letters, numbers, images, and/or symbols) is/are then cut out of retroreflective sheeting having a second color (e.g., white) that is a different color than the first color using a plotter (alternatively, a router could also be used if the sheeting has previously been applied to aluminum). These individually cut indicia are then manually aligned in the necessary position and applied and/or affixed to the sign face using adhesive, welding techniques, or rivets. In instances where the indicia overlap two adjacent sign blanks, the portion of the indicia that does not physically contact either sign blank is cut with a knife. If the sign design includes multi-color indicia, these are typically either screen printed onto the sign (described in greater detail below) or are cut out using numerous colors of optically active sheeting using the method described above.
Alternatively or in addition to the method described above, the indicia may be placed on the retroreflective sheeting by other methods such as, for example, screen printing. In screen printing, a positive or negative image of the characters is first provided on a screen. This is often accomplished by exposing non-masked portions of a photosensitive screen to light and removing the un-sensitized, masked regions by scrubbing. Ink is then forced through the openings in the screen where the photosensitive material was removed onto the retroreflective sheeting. Screen printing is the method of choice for making the more common street signs, such as “stop” and “yield” signs. However, screen printing custom or unique signs (such as, for example, highway and road signs) is costly and inefficient because a separate screen needs to be made for each individual sign.
Once the indicia are affixed to the sign, the finished sign is shipped to the end user. The sign user may then install the signs. Those of skill in the art will appreciate that each of these steps may be modified and that each step can be performed by an entity other than the one described in this specific example.